Impatiens shennongensis Q. Wang & H.P. Deng, 2016

Wang, Qian, Gadagkar, Sudhindra R., Deng, Hong-Ping, Yang, Zhi-Ming & Yu, Feng-Qiong, 2016, Impatiens shennongensis (Balsaminaceae): a new species from Hubei, China, Phytotaxa 244 (1), pp. 96-100 : 97-100

Impatiens shennongensis Q. Wang & H.P. Deng , sp. nov. ( Figs. 1–3 )

Diagnosis: The new species is similar to Impatiens dicentra in having single-flowered peduncles and the upper of the lateral united petals being terminated by a filamentous bristle. However, the differentiating characteristics are that I. shennongensis has a shorter plant height (15–30 cm), with leaves rhombic to sub-rhombic in shape, lateral sepals entire, and navicular lower sepals without a spur. In contrast, I. dicentra is taller (60–90 cm), with ovate or ovate-lanceolate shaped leaves, lateral sepals margins coarsely dentate, lower sepals saccate and constricted into an incurved spur.

Type:— CHINA. Hubei: Shennongjia, Taiziya , margins of bamboo forests, 31°26′51.2″N, 110°11′37.4″E, elev. ca. 2600 m, 10 Aug., 2013, Q.Wang 20130808 (holotype, SWU-00137758 , isotype PE ).

Description

Annual herb, 15–30 cm tall, glabrous. Stems erect, slender, branched. Leaves alternate, petiolate or subsessile on uppermost stem; petioles 0.5–3.5 cm; leaf blades sub-membranaceous, rhombic or sub-rhombic, 1–4× 1–3 cm, apex cuspidate, base cuneate, margin coarsely crenate, teeth 2-lobed, mucronate between lobes, lateral veins in 5–7 pairs, arcuate, midvein abaxially prominent. Inflorescence axillary, 1-flowered, peduncles 0.5–1 cm, glabrous, bracteate above middle; bract solitary, elliptic-ovate, 1–2 mm long, entire, persistent. Flowers white, 1–1.5 cm long; lateral sepals 2, ovate, ca. 2× 1 mm, entire, apex acuminate; lower sepal navicular, spur absent, ca. 5 mm long, mouth truncate, ca. 3 mm across, apex acute; dorsal petal orbicular, ca. 5× 5 mm, base truncate, apex rostellate, not cristate; lateral united petals clawed, with fuchsia striate, ca. 1 cm long, 2-lobed;the upper of the lateral united petals ovate-lanceolate, 3–5 mm long, apex with a filamentous bristle; the lower of the lateral united petals oblong-lanceolate to elliptic, 7–13 mm long, incurved, inner margin curled, auricle obtuse, cornute; Stamens 5, filaments linear, 2–3 mm, anthers small, apex obtuse. Pollen grains elliptic in polar view, 4-colpate, P×E = (6.1–7.1)6.7×(20.8–24.4) 22.4 μm, Sexine ornamentation reticulate, processes in lumen granulate ( Fig. 3A–C ). Ovary 4–5 mm, erect, apex acuminate, glabrous. Capsule 1–1.5 cm long, cylindrical, acuminate, glabrous. Seeds few, oblong ( Fig. 3D ), 2.9–3.4× 1.9–2.3 mm, curvature of periclinal wall of seed coat cells with an undulated pattern ( Fig. 3E ). Cuticle granules visible under higher magnification ( Fig. 3F ).

Etymology: —The epithet shennongensis refers to the type locality, Shennongjia Forest Region, which is rich in plant diversity ( Zhao 2002).

Phenology: —Flowering and fruiting from July to October.

Ecology and Distribution: —The new species occurs at margins of bamboo forests, about 2500 m in elevation. It is currently only known to exist in a small population in the Shennongjia Forest Region.

IUCN Red List category: —Only two populations with about 500 individuals in total of the new species were found in a small area (<4 km 2) in Shennongjia Forest Region. The status of the new species can be classified as Vulnerable (VU D2), based on current information and following the IUCN (The International Union for Conservation of Nature and Natural Resources) guidelines ( IUCN, 2011), but more extensive fieldwork in surrounding similar habitats is needed to accurately assess its conservation status. Fortunately, the species was discovered in the national park and all the natural habitats of the park are protected, although the park is frequented by tourists.

Paratypes: — CHINA. Hubei: Shennongjia, Taiziya , Margins of bamboo forests, 31°26′24.9″N, 110°09′21.3″E, elev. ca. 2300 m, 10 Aug., 2013, Q. Wang 20130822 ( PE, SWU-00137754 ) .

Phenetic relationships: — Impatiens shennongensis is similar to I. dicentra Franchet ex Hooker f. (1908: 268) in some traits such as single-flowered peduncles and the upper of the lateral united petals being terminated by a filamentous bristle. However, the former differs in the following characters: plant height (much shorter: 15–30 cm vs. 60–90 cm); leaf blades (rhombic or sub-rhombic vs. ovate or ovate-lanceolate); leaf margins (coarsely crenate, teeth 2-lobed, and mucronate between lobes vs. crenate-serrate, teeth mucronulate); margins of lateral sepals (entire vs. coarsely dentate); lower sepals (navicular, spur absent vs. saccate, constricted into an incurved, short, 2-lobed spur); flowers (1–1.5 cm long, white with fuchsia striate vs. flowers 4 cm long, yellow).

Figures

FIGURE 1. Impatiens shennongensis Q. Wang & H.P. Deng.—A. Habit.—B. Branch with flower.—C. Flower (front view).—D. Flower (lateral view).—E. Flower (dorsal view).—F. Dorsal petal.—G. Lateral united petal.—H. Lower sepal.—I. Lateral sepals.

FIGURE 2. Impatiens shennongensis Q. Wang & H.P. Deng.—A. Flowering plant.—B. Leaves at the base of stem.—C. Leaves on uppermost stem.—D. Flower (front view).—E. Flower (lateral view).—F. Flower (dorsal view).—G. Lateral sepal.—H. Lower sepal.—I. Dorsal petal.—J. Lateral united petals.—K. Ovary surrounded by stamens.—L. Fruits.

FIGURE 3. SEM micrographs of pollen grains and seeds of Impatiens shennongensis Q. Wang & H.P. Deng.A–C. SEM images of pollen grains.—A, B. Whole view.—C. Sexine sculpture. D–F. SEM images of seeds.—D. Whole view.—E–F. Partial view.